Variable-pole Capacitive Sensor

In the figure, plate 1 is fixed and plate 2 is a movable electrode (moving piece). When the moving piece moves with the measured value, the distance between the two plates changes, thereby changing the capacitance. The capacitance change ΔC is

C0—initial capacitance when the inter-electrode distance is.

This type of capacitive sensor has principle nonlinearity, so in practical applications, in order to improve nonlinearity, increase sensitivity and reduce the influence of external factors (such as power supply voltage and ambient temperature), a differential structure is often made or an appropriate measurement circuit is used to improve its nonlinearity.